Notes:

khulnaa : 'To be uncovered, be unfolded,
be exposed, be laid bare;... -- to be expanded, be widened or enlarged; to
be developed;... to be made known, be disclosed, be divulged, be revealed;...
to be let loose, be set free;... to be dissipated or lost;... -- to acquire
fullness, clearness, brightness, or depth (a colour); to stand out well or
conspicuously, to appear to advantage'. (Platts p.879)

He says, that Pari-faced one, having fallen in love with
the Other, became even more delicate. From the shock of love, to the extent
that her color fades, to that very extent it keeps becoming clearer. That
is, it becomes more pleasing. (221)

He says, from falling in love the beloved's delicacy has
increased somewhat more. As her color kept fading, she kept becoming more
of a Pari. That is, now two things increased: the first is that she became
more delicate than formerly; and the second is that her color keeps becoming
clearer.

[Or:] It's possible that he might say this to tease the beloved,
or that he might be taunting the Rival's passion. (297)

FWP:

Faruqi rightly mentions {13,2}
as an excellent verse for comparison, and I'd add {7,2}
as another (and lesser, though enjoyable) example of Ghalib's face-color wordplay.

Above all, this verse is powered by the cleverly exploited
multivalence of khulnaa . Here are some of the possible
readings that the second line can generate:

=By some effect of her delicacy, her color actually becomes
more visible and evident as the roses slowly fade from her cheeks. Perhaps
because her skin is becoming more pale and delicate, since she's not eating
or sleeping properly? Or perhaps because it now has a more inward and mystical
glow?

=Her color becomes even more radiant and attractive as it
fades, since she's so beautiful that her beauty can't be dimmed by passion;
her new ethereal glow appears to advantage, making her even lovelier than
before. A Pari is, after
all, a creature of special radiance, made from fire rather than (like us mortals)
from mere earth.

=Her 'color' or 'mood, state, condition' (since rang
is so multivalent) is revealed to the world all the more clearly, the more
her cheeks become pale; the secret of her new status as a lover is exposed
for all to see, so that everybody can gossip about it.

This latter reading is the most piquant, since it requires
the meaning of rang to change horses in midstream--
to begin the line as metaphorical, and end it as literal, without the usual
luxury of a repetition. But why not? Obviously it can do this, because it
does do it-- in our minds, as we read the line. The sudden 'flip' is unsettling,
but also enjoyable. (From a flip-- a fillip?)

Note for script fans: it's true that khulnaa
can also be read as khilnaa , 'to bloom'. In order to
squelch this possibility, Arshi carefully provides a pesh
. It's also clear that khilnaa offers a much less interesting
reading, since there's no other 'flower' imagery in the verse. For more on
this pair, see {94,1}.